Like the other components in the fuel system, the internal parts of the injector are constantly bathed in lubricating diesel fuel. However, the injector tip, or nozzle, lives a hellish existence within the cylinder. Its exposed to extremely high temperatures, over 1,000 F, and to air pressures in excess of 500 psi. It also must cope with the byproducts of combustion: soot, water, partially burned hydrocarbons, and acids. Its no wonder that injectors usually require service more often than any other part of the diesel fuel system except filters. Manufacturers recommended service intervals vary. At the very least, injectors should be removed, cleaned, and inspected by an experienced diesel mechanic every 1,000 hours. Often they may need to be rebuilt or replaced (the replacement of inexpensive injectors is more economical than rebuilding). Cruisers wholl be far from maintenance facilities should carry a complete set of spare injectors.